Common names: EIA-232D (RS232-D), ITU-TSS (CCITT) V.24/V.28, ISO 2110
 (at the DTE)
 (at the DTE)
 (at the DCE)
 (at the DCE)
25 PIN D-SUB MALE at the DTE (Computer).
25 PIN D-SUB FEMALE at the DCE (Modem).
| Pin | Name | RS232 | V.24 | Dir | Description | 
|---|---|---|---|---|---|
| 1 | GND | n/a | 101 |  | Shield Ground | 
| 2 | TXD | BA | 103 |  | Transmit Data | 
| 3 | RXD | BB | 104 |  | Receive Data | 
| 4 | RTS | CA | 105 |  | Request to Send | 
| 5 | CTS | CB | 106 |  | Clear to Send | 
| 6 | DSR | CC | 107 |  | Data Set Ready | 
| 7 | GND | AB | 102 |  | System Ground | 
| 8 | CD | CF | 109 |  | Carrier Detect | 
| 9 | - | - | RESERVED | ||
| 10 | - | - | RESERVED | ||
| 11 | STF | 126 |  | Select Transmit Channel | |
| 12 | S.CD | SCF | 122 |  | Secondary Carrier Detect | 
| 13 | S.CTS | SCB | 121 |  | Secondary Clear to Send | 
| 14 | S.TXD | SBA | 118 |  | Secondary Transmit Data | 
| 15 | TCK | DB | 114 |  | Transmission Signal Element Timing | 
| 16 | S.RXD | SBB | 119 |  | Secondary Receive Data | 
| 17 | RCK | DD | 115 |  | Receiver Signal Element Timing | 
| 18 | LL | LL | 141 |  | Local Loop Control | 
| 19 | S.RTS | SCA | 120 |  | Secondary Request to Send | 
| 20 | DTR | CD | 108.2 |  | Data Terminal Ready | 
| 21 | RL | RL | 140 |  | Remote Loop Control | 
| 22 | RI | CE | 125 |  | Ring Indicator | 
| 23 | DSR | CH | 111 |  | Data Signal Rate Selector | 
| 24 | XCK | DA | 113 |  | Transmit Signal Element Timing | 
| 25 | TI | TM | 142 |  | Test Indicator | 
  Note: Direction is DTE (Computer) relative DCE (Modem).
  Note: RS232 column is RS232 circuit name.
  Note: ITU-T column is ITU-TSS V.24 circuit name.
  Note: Do not connect SHIELD(1) to GND(7).
| Contributor: | Joakim Ögren, Petr Krc | 
| Source: | ? | 
  Copyright © The Hardware Book Team 1996-2004.
  May be copied and redistributed, partially or in whole, as appropriate.
  Document last modified: 2002-01-13